Some time ago I came across the Wolphilink Interface. It's a small box which connects an smartphone to a Yaesu FT-817/857/897 transceiver. I was about to buy one, but the interface was quite expensive, especially if you include the optional cables and the shipping to my QTH in Germany. I googled a bit and found an interface built by Christian Petersen, DD7LP. I made the decision to take a closer look on his schematic diagram and built my own interface to use APRSdroid and PSKdroid on my FT-817. Luckily Christian also provided a buying list besides the schematic diagram. As I don't have any knowledge and also no tools to etch a circuit board, I first planned to build the circuit on a simple stripboard.

In this article I will describe how I built a cheap DIY 18650 Lithium-Ion battery pack for my Yaesu FT-817. After 65 SOTA-activations and other outdoor operations like IOTA, WWFF I had to reduce some addional weight of my „go-bag“. I already went from RG-58 coax to RG-174 and also scaled-down the diameter of the antenna wire, but this is a different story. So I looked what is on the regular market and found a lot of people in the amateur radio scene who are using Li-Po (lithium polymer) packs. Those packs are usually made for RC purposes and in the first moment I thought that they perfectly matches all of my needs. They are cheap ($15 per 2500mAh pack) and a 3S pack (3 cells in series) gives 11.1V nominal output.

I used the sunday last week to built the SOTAbeams Mountain Tuner kit for 40-17m. After I built my own tiny EFHW-tuner, I ordered the SOTAbeams kit in the UK, which arrived 7 days after my order here in Germany. I needed a little bit more than 60 minutes for everything including testing. I used the instructions some weeks ago to built the same tuner out of stuff I had in the junkbox. I wanted to compare my work with the commercial tuner and also I liked the design with the plate. You see my construction on one of the photos. The SOTAbeams one was much easier to built, it has a very smart design. For some 18 bucks this tuner is a must have.I went to my local GMA summit (DA/SR-059) to test the tuner with my ultralight linked endfed, which I posted some days ago here in the group.

I go lighter and lighter and lighter... I've built a new EFHW wire for my SOTA-activations last weekend. The antenna is "linked" and is full halfwave on 40/30/20/17m. I went from 0,75mm² (~18 AWG) to 0,14mm² (~26 AWG). Thank you Andreas, DB2AJ for the hint. That saves some additional weight. I use this thin wire together with my homebrew EFHW-QRP tuner. I use a pair of 2,6mm "Zwerg-Stecker" and "Zwerg-Kupplung", with the plastic housing removed, for every link. For optical reasons and also for more mechanical stability, I added som heat-shrinking tube to the connectors. The wire-winder came from SOTAbeams UK and they fit perfect to this easy construction. The whole job did not take longer than about 60 minutes.